1. Field of the Invention
The invention is concerned with improved diesel fuel. More particularly, it is concerned with improving the cetane number thereof by mild, catalytic partial oxidation.
2. Description of the Prior Art
The blending of alcohols, ethers, esters and the like with hydrocarbon fuels for the purpose of increasing the octane number of said fuel is well known in the art. For instance, U.S. Pat. No. 3,904,384 discloses a high octane gasoline produced by mixing suitable hydrocarbons with t-butyl isopropyl ethers; U.S. Pat. No. 3,903,251 mixes butyl alcohol and butyl acetate with hydrocarbons, and U.S. Pat. No. 3,901,664 blends t-butyl alcohol, isopropyl alcohol and methyl alcohol with hydrocarbons to produce high octane motor fuel. These fuels typically contain as much as 40% of oxygenated compounds in the blend to increase the octane number of the gasoline to a level competitive with that of gasoline containing tetraethyl lead, an octane booster in commercial fuels. However, although many oxygenated organic compounds have high octane ratings they are not useful in diesel applications since octane and cetane numbers are inversely related, i.e., a high octane fuel will exhibit poor cetane qualties. Other oxygenates such as perioxides have been used as free radical generators to improve cetane number in additive level quantities (&lt;.about.1%). However, the use of such specifically synthesized pure compounds is often limited by such factors as cost.
Thus, U.S. Pat. No. 4,046,522 is concerned with providing a converter system for converting a low octane, normally liquid hydrocarbon fuel to one of higher octane. In general, 4,056,522 relates to a catalytic converter adapted for installation in the fuel line of an engine to replace the conventional carburetor. There are two separate reactors in the converter arranged so the fuel passes through one and then the other so as to decompose oxygen-containing organic compounds to CO and hydrogen. The catalyst may be alumina, zinc chromite, copperzinc chromite, manganese chromite, supported iron and cobalt, etc.